The present invention relates to an incinerator for municipal refuse which is designed so that the amount of unburnt gas generated therefrom is minimized.
As means of minimizing the amount of unburnt gas generated from an incinerator, various techniques have heretofore been proposed: for example, "Refuse Incinerating Method and Apparatus therefor" disclosed in Japanese Patent Laid-Open (KOKAI) No. 63-282414, and "Apparatus for Controlling NO.sub.x and Unburnt Gas Generated from Fluidized-Bed Incinerator" disclosed in Japanese Patent Laid-Open (KOKAI) No. 63-279013.
In either of the above-described techniques, a secondary air injection device is disposed across a combustion chamber to promote mixing of oxygen and unburnt gas by vortex flow produced by the injected air, thereby controlling the generation of harmful substances.
However, in either of the above-described prior arts, the mixing of secondary air and unburnt gas depends upon the penetration force of the injected air (i.e., the flow velocity at which secondary air is blown into the combustion chamber). Accordingly, as the distance from the secondary air injection ports increases, the stirring force becomes weaker rapidly, so that there is a possibility that unburnt gas will pass through a region where the injected secondary air exerts no effect, resulting in a failure to achieve mixing of the unburnt gas and the air. If the number of air injection ports is increased in order to prevent such a problem, the penetration force of the injected air becomes weak undesirably.
Even if a throttle portion is provided in the post-stage as in the apparatus disclosed in Japanese Patent Laid-Open (KOKAI) No. 63-282414, unburnt gas that passes without contacting the air may also pass through the throttle portion without contacting the air.